Navigation system



FIG. 1 is a top front right side perspective view of a navigation system showing my new design;

FIG. 2 is a top plan view thereof;

FIG. 3 is a front elevational view thereof;

FIG. 4 is a right side elevational view thereof;

FIG. 5 is a rear elevational view thereof;

FIG. 6 is a bottom plan view thereof; and,

FIG. 7 is a top rear left side perspective view thereof. 

The ornamental design for a navigation system, as shown and described. 